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Will You Precrastinate? Sensitivity to Potential Performance Costs And Effort in Chronic Cannabis Users And Non-users
Get PDFWe examined whether those who chronically use cannabis (chronic users), compared to those who do not use cannabis (non-users), tend to precrastinate (start or complete a subgoal as soon as possible) and engage in reactive (vs. proactive) decision-making incurring greater potential costs in task performance and perhaps costs in cognitive and physical effort. Participants walked down a hallway and retrieved two full cups of water (one near and one far from their starting position) in the order of their choice and carried both back to their start location with the goal of not spilling. First-cup choice (near or far) and attributions of first-cup choice were recorded. Counter to expectations, chronic users tended to choose the far cup first (i.e., avoided precrastination), the more efficient choice, and this tendency was not different from non-users. Participants’ attributions confirmed that those who chose the far cup first likely engaged in proactive decision-making while those who chose the near cup first likely engaged in reactive decision-making. Additionally, chronic users and non-users utilized proactive control in the AX-Continuous Performance Task even though chronic users had lower short-term and working memory span scores. These results contradict research suggesting chronic users (vs. non-users) are more impulsive, lack inhibitory control, tend to invest physical effort regardless of reward, and tend not to invest cognitive effort for reward. We suggest that chronic cannabis use may not impair decision making as profoundly as previously thought if individuals are motivated by potential consequences of their decisions in tasks with low memory demand
Veterinary Medicine Extension Newsletter, April 2025
No full textIncluded in this newsletter: Lupine-induced Crooked Calf Syndrome; Cache Valley virus; The Effects of Heat Stress on Dairy Cattle Development, Health, and Performanc
Shock Compression of Cemented Tunsgten Carbides to 100 GPa Structure of Shock Wave, Hugoniot relationships, evolution of elastic moduli and strength
Get PDFThere has been a significant interest in the development of tungsten carbide (WC)–based cermets for applications related to extreme thermomechanical environments. For example, the Department of Defense is actively exploring the use of WC cermets for armor and anti-armor applications, while the civilian industry is pursuing their use as cutting tool materials, cold forging dies, and surface coatings, to name a few. Given the extreme dynamic environments in which cemented WCs are targeted to operate, a comprehensive understanding of their shock and impact behavior is of paramount importance. In this study, plate impact experiments are conducted on cemented tungsten carbides (WC) with cobalt binders of 3.7 and 6.0 wt. % to investigate their dynamic high pressure response to ∼ 100 GPa. The shock wave profiles measured by laser interferometry show propagation of steady structured waves. Standard impedance matching procedures are used to determine in-material shock quantities, including Hugoniot relations in the shock velocity versus particle velocity (Us − up) and longitudinal stress versus specific volume (P − V ) planes. The Hugoniot elastic limit of the samples is found to be controlled by the weight % of the cobalt binder and is determined to be 4.45 ± 0.29 GPa for the cemented WC with 3.7 wt.% cobalt and 3.72 ± 0.24 GPa for the 6.0 wt.% cobalt binder. Both grades show a non-linear Us − up relationship depending on whether the particle velocity is in the strength-dominated or hydrodynamic regime. In the strength dominated regime, a non-linear decrease in Us is observed as up increases from ambient to the material’s hydrodynamic limit. In the hydrodynamic regime, the Us − up Hugoniot is linear and is determined to be Us = 4.97(±0.006) + 1.446(±0.018)up km/s for WC with 3.7 wt.% Co and Us = 4.93(±0.006) + 1.463(±0.017)up km/s for 6 wt. % Co. Both WC grades indicate shear-stress hardening with mean stress immediately after yield, followed by pressure softening, and then a sharp drop in stress carrying capacity as the mean stress increases to ∼ 70 GPa (hydrodynamic limit) and beyond. This behavior is in contrast to pure WC ceramics, which show continued shear-stress hardening with mean stress to ∼ 80 GPa. In addition, the evolution of the elastic properties of cemented tungsten carbides up to 100 GPa is investigated to gain insight into the state of mechanical damage to shock-compressed samples. Eight plate impact experiments are conducted -- three front surface impact and five release wave overtake -- to make simultaneous measurements of Hugoniot states and longitudinal sound speeds in the shock-compressed WC samples with 3.7 wt.% cobalt binder. The sound speeds, together with estimates for the bulk sound speeds derived from the Birch-Murnaghan Equation of State (EoS), are examined to evaluate the elastic moduli -- longitudinal, bulk, and shear -- in relation to Hugoniot stress. In the studied Hugoniot states, the longitudinal and bulk sound velocities are observed to rise linearly with the longitudinal stress. This increase in sound speeds corresponds to an increase in both the longitudinal and the bulk moduli as a function of the Hugoniot stress. However, the increase in the longitudinal modulus is relatively small compared to predictions from theoretical models that consider the pressure and temperature dependency of elastic moduli without any damage. Meanwhile, the shear modulus remains nearly unchanged around 310 GPa in the explored Hugoniot states, which is significantly lower than the predictions of the Steinberg-Guinan model, assuming no damage. Initially, the Poisson ratio falls from its ambient value of 0.208 to ∼ 0.199 when the Hugoniot stress is around 10 GPa, suggesting microstructural consolidation in WC at low initial stress. However, as the Hugoniot stress increases to approximately 310 GPa, the Poisson ratio increases to 0.317, suggesting a reduction in shear moduli with increasing stress. After an initial increase, the product of density and Grüneisen parameter (ρΓ) remains fairly constant for volumetric strains around 0.07. The maximum estimated average temperature increase reaches about 286 ◦C at the highest Hugoniot stress level used in the study. Finally, a thermodynamically-consistent, finite-strain, rate- and pressure- dependent constitutive framework is implemented to analyze the shock-compression behavior of cemented tungsten carbides to 100 GPa. Central to this framework is the use of logarithmic strain with a set of invariant basis that allow the Cauchy stress tensor to be expressed as a sum of three response terms that are mutually orthogonal, thus permitting a complete separation of the deviatoric and volumetric (pressure) response. An overstress viscoplasticity model that includes strain and strain rate hardening along with thermal softening is used to represent the deviatoric response, while a complete Mie-Grüneisen equation of state (EoS) is used to obtain the pressure response. Using this formulation, the shock-induced compression behavior of cemented tungsten carbides with 3.7 wt. % of cobalt binder were analyzed to better understand the structure of the measured shock profiles and the associated in-material shock quantities to ∼100 GPa. Of particular interest was the evolution of material strength, material inelasticity, and sample temperatures in the shocked tungsten carbide samples. The simulations were reasonably successful in capturing the interfacial particle velocity profiles using a fixed set of model parameters, except for the rate sensitivity parameter, which was kept at 4.0 for pressures up to 40 GPa and then gradually reduced to 2.0, as Hugoniot pressures approach the hydro-dynamic limit of the material. This variation in the rate sensitivity parameter was found to be necessary to capture the high rate sensitivity of the WC just above its HEL and its reduced rate sensitivity at the higher pressures as the samples approach their hydrodynamic limit. The simulated and experimental profiles are observed to deviate considerably after the arrival of the release wave from the back of the flyer. These deviations become more prominent as the peak Hugoniot stresses are increased beyond the HEL of the WC samples, and are understood to be due to the change in deformation and failure physics/mechanics with increase in impact stress
WATER AND SOIL QUALITY MANAGEMENT FOR ROOT HEALTH AND MANAGEMENT OF VERTICILLIUM WILT IN POTATO
Get PDFThis dissertation investigates the use of organic amendments and irrigation strategies to improve soil health, root development, water retention, and disease suppression in potato (Solanum tuberosum L.) production. The work integrates field experiments, laboratory measurements, and in vitro evaluations to assess soil physical, chemical, biological, and plant-based responses to different soil management approaches. The first study investigated the impact of mustard green manure (MGM), organic compost (OC), compost tea (CT), and NPK fertilizer under two irrigation regimes (2 liters every 2 days and 4 liters every 4 days), with and without V. dahliae inoculation on potato growth, soil quality, and verticillium wilt. MGM significantly enhanced root growth and increased tuber yield by 14.5% compared to NPK, while reducing verticillium wilt severity by 53.3%. The second study focused on the hydrological effects of these amendments by measuring volumetric water content in situ and modeling soil water retention characteristics using Hyprop analysis. OC and MGM improved soil physical properties, water content, and plant available water. The third study evaluated in vitro the effect of eight different CTs brewed at 3, 6, and 10 days on the colony growth of Verticillium dahliae. The pure fungal culture was exposed to each CT in both unsterilized and filter-sterilized conditions by both direct and volatile exposure. CTs inhibited mycelial growth up to 90.1% via direct exposure and 71.7% via volatile effects, with peak efficacy observed at 6 days of brewing. Sterilized CTs showed reduced but still notable suppression with direct exposure, but not volatile effects. The findings of this dissertation highlight the effectiveness of integrating organic amendments with optimized irrigation strategies to enhance soil quality and crop productivity in sandy soils. Compost teas exhibit strong potential as sustainable biocontrol agents against V. dahliae
EXAMINING COGNITIVE SELF-EFFICACY AS A MODERATOR OF THE RELATIONSHIP BETWEEN COMPENSATORY STRATEGY QUALITY AND PROSPECTIVE MEMORY ACCURACY
Get PDFRecent research has established compensatory strategy quality as a stronger predictor of prospective memory accuracy than a simple count of strategies. However, individuals appear to benefit differentially from strategies, and factors that influence this relationship remain unclear. The present study aimed to examine mid-life and older adults’ cognitive self-efficacy as a potential moderator of the relationship between compensatory strategy quality and prospective memory performance. One hundred eighty-five mid-life and older adult participants completed two testing sessions from their own homes through video conferencing (Zoom). Participants were presented with two in-session prospective memory tasks and two real-world prospective memory tasks designed to be completed independently in the future. Participants were given time to plan and encouraged to use their typical strategies. The examiner collected detailed information about strategies utilized at follow-up testing. Participants also completed a battery of standard neuropsychological tests and questionnaires, including a questionnaire on cognitive self-efficacy. Cognitive compensation self-efficacy emerged as a significant moderator of the relationship between compensatory strategy quality and prospective memory performance of the in-session event-based task and real-world time-based task. In both models, it was revealed that higher cognitive compensation self-efficacy facilitated effective application of strategies and task completion, particularly for individuals who employed lower quality strategies. Findings highlight cognitive self-efficacy as an important intervention target that may enhance effective use of compensatory strategies to support completion of everyday prospective memory tasks based on certain characteristics of the prospective memory cue
Washington County Resource Guide - Idaho
Get PDFCounty level and region-specific resource guides focused on mental health and substance use